In numerous technical fields such as chemistry, biology, medicine or environmental science, for example, it is necessary to analyse, process or react biological materials (e.g. fluids). For this purpose the fluids or materials are filtered, cooled, heated, broken down into their constituents, washed or pipetted by various methods or treated in other ways. It is frequently necessary to go through a long and complex sequence of processing steps in order to prepare the biological material. Moreover, in many cases, large collections of different materials have to be processed in accordance with the same sequence, or series of the same materials have to be processed in parallel. This can be time consuming, limits the throughput and is prone to breakdown.
The processing of biological materials is used for example in the field of the extraction and/or purification of biomolecules such as nucleic acids or proteins. For example, a well known method of purifying biomolecules is based on the steps of providing access to the contents of a biological sample (“lysis”), selectively binding the constituents of the contents of the biological sample to a solid support or carrier material (“binding”), eliminating unwanted ingredients from the solid support or carrier material (“washing”), and dissolving the desired constituent (“eluting”).
In order to permit the desired absorption and desorption during the purification of the biomolecules, special filter elements have been developed which are formed from silica gel, for example, and which are porous or matrix-like on the one hand in order to allow a liquid to pass through the filter element and, on the other hand, have a surface to which the molecules bind in a specific or non specific process. In other purification processes, biomolecules are retained on filter elements simply by the effect of size exclusion. If a liquid which contains a biomolecule such as a nucleic acid, for example, passes through the filter element, the biomolecules or part thereof are retained in the filter element in any case, while the remainder passes through the filter element.
Moreover, in order to obtain the biomolecule from the filter element, an eluting liquid such as nuclease-free water is passed over the filter element in order to desorb the biomolecule. In this way the desired biomolecule is released from the filter element (eluted) and caught in a vessel. Such filter elements are frequently designed as membranes which are either arranged in individual vessels having an inlet opening and an outlet opening or are arranged in multiwell plates. The filter elements are processed either by centrifuging (spin format) or using apparatus based on vacuum technology. Individual vessels having an inlet opening and an outlet opening, which have a membrane and which can be used in a centrifuge, are also known in the form of columns, centrifuge columns, filter vessels, chromatography columns, columns, spin columns or single spin columns.
Generally, the advantages of the centrifuge process over the vacuum-based methods are the higher degree of purity, higher concentration and reduced risk of cross-contamination. In general, the best results for the purification of the biomolecules in terms of quality and concentration are obtained with the centrifuge columns (single spin tubes) which are processed under a high gravity field (>10,000×g), as this permits minimum cross contamination and maximum recovery of the desired substance from the membrane. One disadvantage, however, is the labour-intensive manual treatment of the centrifuge columns, which increases the risk of error and the processing time, especially when different samples have to be treated or processed simultaneously. A higher degree of standardisation and automation as well as a faster throughput can be achieved by using multiwell plate formats. However, this involves compromises with regard to quality and/or quantity.
QIAGEN offer a wide range of purification procedures and the necessary products for different biomolecules from a range of biological samples, based on the fundamental principle of the “bind-wash-elute” procedure. For this purpose, different filter materials and equipment are used as described for example in WO 03/040364 or U.S. Pat. No. 6,277,648. The commercially available product “QIAGEN QIAprep Spin Miniprep Kit” discloses for example a typical purification sequence and supplies standardised QIAprep columns and 2 ml collecting vessels for use in a centrifuge together with some reagents and buffers.
There are a number of publications on the subject of processing biological materials. U.S. Pat. No. 6,060,022, for example, discloses an automated system for sample processing which comprises an automated centrifuge apparatus. U.S. Pat. No. 5,166,889 describes a collecting system for blood in which a plurality of collecting vessels are positioned in a carrier wheel for direct access. US 2004/0002415 describes an automated centrifuge system for automatically centrifuging fluids which contain biological material such as e.g. nucleic acids in a general centrifuge. WO 2005/019836 describes an apparatus for processing fluid samples. WO 00/38046 describes an automated apparatus for loading a centrifuge, in which columns of the centrifuge are brought into play using an automated routing system. EP 122772 describes a chemical manipulator for use with reaction vessels. GB 2235639 describes a centrifuge with a protective jacket surrounding the rotating container.
One disadvantage of the existing automation system is that the processes which they support do not provide the high quality standard of the centrifuge columns and cannot function simultaneously with little or no manual intervention.